Don't require "debug" in brew tests - it's in our RSpec config

Library/Homebrew/dev-cmd/tests.rb

@@ -22,7 +22,7 @@ class Tests < AbstractCommand
                description: "Include tests that use the GitHub API and tests that use any of the taps for " \
                             "official external commands."
         switch "--debug",
-               description: "Enable debugging using ruby/debug."
+               description: "Enable debugging using ruby/debug, or surface the standard `odebug` output."
         switch "--changed",
                description: "Only runs tests on files that were changed from the master branch."
         switch "--fail-fast",
@@ -45,8 +45,6 @@ def run
         # Given we might be testing various commands, we probably want everything (except sorbet-static)
         Homebrew.install_bundler_gems!(groups: Homebrew.valid_gem_groups - ["sorbet"])
 
-        require "debug" if args.debug?
-
         HOMEBREW_LIBRARY_PATH.cd do
           setup_environment!